TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to a structural link for permanently connecting two
subassemblies of a rail vehicle assembly, such as two adjacent vehicle bodies or a
vehicle body and a running gear.
BACKGROUND ART
[0002] A structural link for permanently connecting two subassemblies of a rail vehicle
assembly is disclosed in
US 2009/0008963 A1. This structural link comprises an energy absorption unit comprising a widened portion
and a permanently deformable cylinder, which defines a reference axis. It further
comprises a piston comprising an end portion provided with a non-deformable piston
head, which is such as to effect a radial expansion of the permanently deformable
cylinder while moving parallel to the reference axis within the permanently deformable
cylinder in a stroke direction from an service position towards an end position. The
piston is further provided with a guide for guiding a relative translation motion
between the piston and the permanently deformable cylinder from the service position
to the end position of the piston head. The guide protrudes from the piston head in
the stroke direction and slides into the permanently deformable cylinder ahead of
the piston head. The length of the permanently deformable cylinder is therefore greater
than the stroke of the piston head from the service position to the end position to
accommodate the guide in the end position. The piston is further provided with a bushing
for receiving a pivot pin for articulating an end section of a coupling rod. The bushing
defines a pivot axis perpendicular to the reference axis of the permanently deformable
cylinder. The piston does not have a piston rod linking the bushing to the piston
head. Hence, in the service position, the bushing protrudes outside the widened portion
of the energy-absorption unit, but is very close to the widened portion. This may
hinder the stroke motion of the piston head into the permanently deformable cylinder
if the coupling rod is at angle with the reference axis of the permanently deformable
cylinder during a collision.
SUMMARY OF THE INVENTION
[0003] The invention aims to provide an improved structural link for permanently connecting
two subassemblies of a rail vehicle assembly.
[0004] According to a first aspect of the invention, there is provided a permanent structural
link for permanently linking a first subassembly of a rail vehicle assembly with a
second subassembly of the rail vehicle assembly, wherein the first subassembly and
the second subassembly consist either of a first vehicle body and a second vehicle
body or of a vehicle body and a running gear, wherein the structural link comprises:
- an energy absorption unit comprising a permanently deformable cylinder, which defines
a reference axis and a widened portion, which has an inner cross-sectional area greater
than the permanently deformable cylinder,
- a piston comprising an end portion provided with a non-deformable piston head, wherein
the piston head in a service position is received in the widened portion of the energy
absorption unit, wherein the piston head is such as to effect a radial expansion of
the permanently deformable cylinder while moving within the permanently deformable
cylinder in a stroke direction parallel to the reference axis, and
- an annular guide for guiding a relative translation motion between the piston and
the permanently deformable cylinder in the stroke direction,
[0005] More specifically, the piston comprises a piston rod protruding from the end portion
in a direction parallel to the reference axis and opposed to the stroke direction,
the piston rod is provided with an outer cylindrical sliding surface, and the annular
guide is fixed relative to the widened portion of the energy absorption unit and has
an inner diameter such as to be in sliding contact with the outer cylindrical sliding
surface of the piston rod at least when the piston head, after leaving the service
position, moves towards the end position.
[0006] The permanently deformable cylinder does not need to have a length greater than the
stroke of the piston head between the service position and the end position, since
it does not have to accommodate the guide.
[0007] The piston rod and the annular guide cooperate to ensure that the piston head does
not deviate from the stroke direction. During the stroke, the distance between the
piston head and the annular guide increases while the distance between annular guide
and the opposite end of the piston rod is reduced.
[0008] In practice, it is possible to define a predetermined collision threshold and a predetermined
service limit lower than or equal to said collision threshold such that upon application
of any collision load above said predetermined collision threshold in an axial direction
parallel to the reference axis the piston head effects said radial expansion of the
permanently deformable cylinder while moving parallel to the reference axis within
the permanently deformable cylinder from the service position towards the end position,
whereas upon application of any proof load or fatigue load below the predetermined
service limit in the axial direction the piston head remains in the service position.
[0009] According to a preferred embodiment, the annular guide in the service position is
press-fitted onto a cylindrical seat of the piston rod. The press-fitted connection
defines a force threshold below which axial forces are transmitted between the piston
and the annular guide without deformation of the energy absorption unit. Above said
threshold, the piston rod separates from the annular guide and the piston starts moving
in the stroke direction while the piston rod slides within the annular guide.
[0010] According to a preferred embodiment, the annular guide in the service position bears
axially against a shoulder of a collar of the widened portion of the energy-absorption
unit and the shoulder of the collar of the widened portion of the energy-absorption
unit faces a direction that has an axial component opposite to the stroke direction.
The shoulder of the widened portion of the energy-absorption unit ensures that the
annular guide does not move in the stroke direction relative to the energy-absorption
unit.
[0011] Preferably, the annular guide is secured to the collar of the widened portion of
the energy-absorption unit by means of fixing elements such as screws, bolts or rivets.
The fixing elements ensure that the annular guide does not move relative to the energy-absorption
unit in the axial direction opposite to the stroke direction. Preferably, the permanent
structural link further comprises a mounting plate, wherein the collar of the widened
portion of the energy-absorption unit is sandwiched between the mounting plate and
the annular guide and the fixing elements secure the annular guide to the mounting
plate through holes provided in the collar of the widened portion of the energy-absorption
unit.
[0012] According to one embodiment, the collar of the widened portion of the energy-absorption
unit is welded, preferably butt welded with an end of the permanently deformable cylinder.
Alternatively, the energy absorption unit can be formed in one piece.
[0013] According to a preferred embodiment, the annular guide in the service position bears
axially against a shoulder of the end portion of the piston, wherein the shoulder
of the end portion of the piston faces a direction that has an axial component opposite
to the stroke direction. The shoulder of the end portion of the piston ensures that
the structural link can withstand traction forces in the reference direction, i.e.
forces that tend to pull the piston in the direction opposite to the stroke direction.
[0014] To avoid any undesired play and wear during the lifetime of the structural link,
the annular guide preferably bears axially against the shoulder of the end portion
of the piston with a predetermined axial preload and the piston head in the service
position bears axially against a shoulder of the widened portion of the energy-absorption
unit with a predetermined axial preload, equal in magnitude to the axial preload between
the annular guide and the shoulder of the end portion of the piston.
[0015] According to one embodiment, the annular guide is made of a material having a Vickers
hardness greater than 600 HV, preferably greater than 630 HV. The hardness of the
annular guide contributes to the absence of deformation or play of the permanent structural
link during its lifetime in the service position.
[0016] According to one embodiment, the piston head in the service position is press-fitted
into the widened portion of the energy-absorption unit. Preferably, the piston head
has a tapered end face and the shoulder of the widened portion of the energy-absorption
unit is tapered.
[0017] The piston head is preferably annular.
[0018] According to one embodiment, the end portion of the piston is made in one piece.
Alternatively, the end portion of the piston can be made of several parts including
a piston head body and the non-deformable piston head. The piston head is preferably
press-fitted or otherwise affixed to a body of the end portion. According to a preferred
embodiment, the piston head is press-fitted to the body of the body of the end portion
and the connection is secured by means of fixing elements such as screws, preferably
locked with glue.
[0019] According to a preferred embodiment, the non-deformable piston head is preferably
made of a material having a Vickers hardness greater than 650 HV, preferably greater
than 700HV. The high hardness of the piston head ensures a controlled expansion of
the permanently deformable cylinder.
[0020] According to one embodiment, the piston rod is tubular.
[0021] According to one embodiment, the end portion of the piston and the piston rod are
made in a single piece, preferably a tubular piece.
[0022] Advantageously, the permanent structural link further comprises a coupling eye integral
with an end of the piston opposed to the end portion. The coupling eye is part of
a hinge connection or of a ball joint.
[0023] According to another aspect of the invention, the hinge connection or ball joint
is part of the structural link.
[0024] According to another aspect of the invention, there is provided a a rail vehicle
assembly comprising a first subassembly and a second subassembly of a rail vehicle
assembly, wherein the first subassembly and the second subassembly consist either
of a first vehicle body and a second vehicle body or of a vehicle body and a running
gear, characterised in that the rail vehicle assembly further comprises a permanent
structural link according to any one of the preceding claims for linking the first
subassembly with the second subassembly. Preferably, the reference axis of the permanent
structural link is parallel to a median vertical longitudinal plane of the rail vehicle
assembly, and preferably parallel to a longitudinal axis of the rail vehicle assembly.
[0025] As stated above, it is possible to define a predetermined collision threshold and
a predetermined service limit below said collision threshold such that upon application
of any collision load above said predetermined collision threshold in an axial direction
parallel to the reference axis the piston head effects said radial expansion of the
permanently deformable cylinder while moving parallel to the reference axis within
the permanently deformable cylinder from the service position towards the end position,
whereas upon application of any proof load or fatigue load below the predetermined
service limit in the axial direction the piston head remains in the service position.
[0026] The predetermined service limit is more than a standard proof load and a standard
fatigue load of the rail vehicle according to the applicable standard load cases.
[0027] The predetermined service limit is more than a standard proof load and a standard
fatigue load of the rail vehicle according to the applicable standard.
BRIEF DESCRIPTION OF THE FIGURES
[0028] Other advantages and features of the invention will then become more clearly apparent
from the following description of a specific embodiment of the invention given as
non-restrictive examples only and represented in the accompanying drawings in which:
- figure 1 is a side view of a region of a train set comprising two adjacent car bodies
and a running gear;
- figure 2 is a longitudinal cross-section of a detail of figure 1;
- figure 3 is an isometric view from below of some parts of the region of a the train
set illustrated in figure 1;
- figure 4 is an isometric view of a structural link between the running gear and one
of the adjacent car bodies shown in figure 1;
- figure 5 is an axial section of the structural link of figure 4, along section plane
V-V of figure 8;
- figure 6 is an axial section of the structural link of figure 4, along section plane
VI-VI of figure 8;
- figure 7 is an axial section of a detail of the structural link of figure 4, along
section plane VII-VII of figure 8;
- figure 8 is a front view of the structural link of figure 4.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0029] With reference to Figures
1 to
3, a train set
10 comprises a first car body
12, a second car body
14 and a running gear
16 located below adjacent ends of the first and second car bodies,
12, 14. A structural link
18 forms a permanent connection between the end of the first car body
12 and the second car body
18. The structural link comprises an energy absorption unit
20 fixed to the end of the first car body
12, a ball joint housing
22 fixed to the second car body
18 and a piston
24 for connecting the energy absorption unit
20 to the ball joint housing
22. The ball joint housing
22 has a vertical extension that protrudes though an aperture in a frame
26 of the running gear
16 and is linked to the frame
26 by longitudinal resilient members
27, which transfer longitudinal forces between the frame
26 of the running gear
16 and the ball joint housing
22.
[0030] The energy absorption unit
20 illustrated in figures
4 to
8 comprises a permanently deformable cylinder
28, which defines a reference axis
100, and an annular widened portion
30 at an open end of the permanently deformable cylinder
28. The opposite end of the permanently deformable cylinder
28 is closed with a cap
32. The axial direction
200 parallel to the reference axis
100 and directed from the open end towards the cap
32 is called stroke direction. The reference axis
100 is located in a median longitudinal vertical plane of the first car body
12. The reference axis
100 is preferably horizontal.
[0031] The widened portion
30 is coaxial with the permanently deformable cylinder
28 and has a slightly larger inner diameter than the permanently deformable cylinder
28. The widened portion
30 comprises a collar
34 that protrudes radially so as to form an annular planar shoulder
36 that faces in a direction opposite to the stroke direction
200. The collar
34 of the widened portion
30 is provided with a set of axial through holes
38. The collar
34 is welded, preferably butt welded with a widened extension
40 of the permanently deformable cylinder
30.
[0032] The piston
24 comprises a piston rod
42 and two opposite end portions, namely first end portion
44 which, in the service position depicted in the figures, is received in the widened
portion
30 of the energy absorption unit
20, and a second end portion
46 opposed to the first end portion and provided with a coupling eye
48 for receiving the ball joint
49 fixed to the ball joint housing
22. The piston rod
42 protrudes from the first end portion
44 in a direction parallel to the reference axis
100 and opposed to the stroke direction
200. The piston rod
42 is tubular, as well as the first end portion
44.
[0033] The first end portion
44 of the piston
24 comprises a piston head body
50 integral with the piston rod
42 and a non-deformable tapered annular piston head
52 protruding at the free end of the first end portion
44 in the stroke direction
200. The piston head
52 is press-fitted onto the piston head body
50. The material of the piston head
52 has a greater hardness than the material of the permanently deformable cylinder
28. The hardness of the piston head body
50 is preferably greater than 650 HV, preferably greater than 700 HV. The piston head
52 in the service position bears axially against a tapered shoulder
54 of the widened portion of the energy-absorption unit
30, which marks the transition between the widened extension
40 of the widened portion
30 and the permanently deformable cylinder
28.
[0034] The first end portion
44 of the piston
24 is further provided with an annular planar shoulder
56, which faces the direction opposite to the stroke direction
200.
[0035] The energy absorption unit
20 further comprises an annular guide
58 for maintaining the piston
24 in the service position and guiding the piston
24 in translation parallel to the reference axis
100 in the stroke direction
200 relative to the permanently deformable cylinder.
[0036] The annular guide
58 bears axially against the shoulder
36 of the collar
34 of the widened portion
30 of the energy-absorption unit
20 and is provided with through holes
60 coaxial with the through holes
38 of the collar
34. The annular guide
58 has a hardness, which is preferably greater than 600 HV, preferably greater than
630 HV.
[0037] The structural link
18 further comprises a mounting plate
62 for securing the structural link
18 to the end of the first car body
12. The mounting plate
62 is provided with threaded holes
64 that are coaxial with the through holes
60 of the annular guide
58 and the through holes
38 of the collar
34. The collar
34 is sandwiched between the annular guide
58 and the mounting plate
62. Fixing elements such as screws
66 engaged in the through holes
60, 38 and threaded holes
66 are used to secure the annular guide
58 and the collar
34 to the mounting plate
62.
[0038] When the screws
66 are tightened with a predetermined torque, the annular guide
58 bears axially against the shoulder
56 of the end portion
44 of the piston
24 with a predetermined axial preload and the piston head
52 bears axially against the tapered shoulder
54 of the widened portion
40 of the energy-absorption unit
30 with a predetermined axial preload, equal in magnitude to the axial preload between
the annular guide
58 and the shoulder
56 of the end portion
44 of the piston
24.
[0039] The mounting plate
62 is further provided with a set of though holes
68 for fixing the mounting plate
62 to the end of the first car body
12, by means of fixing elements
70.
[0040] The annular guide
58 in the service position is press-fitted onto a cylindrical seat
72 of the piston rod
42. The piston rod
42 is provided with a smooth outer cylindrical sliding surface
74, which has a diameter slightly smaller than the cylindrical seat
72.
[0041] The structural link
18 operates as follows.
[0042] The tight sandwiched connection between the end portion
44, the tapered shoulder
54 of the energy-absorption unit
20 and the annular guide
58 is such as to remain without play and without plastic deformation upon application
of any proof load or fatigue load below a predetermined service limit in the axial
direction the piston
24. To this end, the axial preload of the annular guide
36 against the shoulder
56 of the end portion
44 of the piston
24 in the absence of external force is preferably greater than the predetermined service
limit.
[0043] However, whenever a collision load above a predetermined collision threshold in an
axial direction parallel to the reference axis
100 is applied, the press fit connection between annular guide
58 and the seat
72 is overcome and the piston head
54 effects a radial expansion of the permanently deformable cylinder
28 while moving parallel to the reference axis
100 in the stroke direction
200 within the permanently deformable cylinder
28 from the service position towards an end position closer to the cap
100. The annular guide
58 has an inner diameter such as to be in sliding contact with the outer cylindrical
sliding surface
74 of the piston rod
42 when the piston head
54, after leaving the service position, moves towards the end position.
[0044] The predetermined service limit is more than a standard proof load and a standard
fatigue load of the rail vehicle according to the applicable standard load cases and
less than the predetermined collision threshold.
[0045] In practice, the axial preload of the annular guide against the shoulder of the piston
head in the absence of external force is greater than the predetermined service limit
and smaller than the predetermined collision threshold.
[0046] The invention is not limited to this embodiment. As a variant, the end portion
44 of the piston is made in one piece, i.e. the piston head
54 and piston head body
50 are made in one piece. The energy absorption unit
20 can also be formed in one piece, i.e. the collar
64 can be made in one piece with the permanently deformable cylinder
28. The cap
32 is optional. The mounting plate
62 can be integral with the collar
64. The piston rod can
42 be a solid cylinder rather than a tubular cylinder.
[0047] The structural link
18 can be used in other train configurations, e.g. between two vehicle bodies
12, 14, or between a vehicle body
12 and a running gear
16 that is not a Jacob-type bogie.
1. A permanent structural link (18) for permanently linking a first subassembly of a
rail vehicle assembly with a second subassembly of the rail vehicle assembly, wherein
the first subassembly and the second subassembly consist either of a first vehicle
body (12) and a second vehicle body (14) or of a vehicle body (12) and a running gear
(16), wherein the structural link (18) comprises:
- an energy absorption unit (20) comprising a permanently deformable cylinder (28),
which defines a reference axis (100) and a widened portion (30), which has an inner
cross-sectional area greater than the permanently deformable cylinder (28),
- a piston (24) comprising an end portion (44) provided with a non-deformable piston
head (52), wherein the piston head (52) in a service position is received in the widened
portion (30) of the energy absorption unit (20), wherein the piston head (52) is such
as to effect a radial expansion of the permanently deformable cylinder (28) while
moving within the permanently deformable cylinder (28) in a stroke direction (200)
parallel to the reference axis (100), and
- an annular guide (58) for guiding a relative translation motion between the piston
(24) and the permanently deformable cylinder (28) in the stroke direction (200),
characterised in that the piston (24) comprises a piston rod (42) protruding from the end portion (44)
in a direction parallel to the reference axis (100) and opposed to the stroke direction
(200), the piston rod (42) is provided with an outer cylindrical sliding surface (74),
and the annular guide (58) is fixed relative to the widened portion (30) of the energy
absorption unit (20) and has an inner diameter such as to be in sliding contact with
the outer cylindrical sliding surface (74) of the piston rod (42) at least when the
piston head (52), after leaving the service position, moves towards the end position.
2. The permanent structural link (18) of claim 1, wherein the annular guide (58) in the
service position is press-fitted onto a cylindrical seat (72) of the piston rod (42).
3. The permanent structural link (18) of any one of the preceding claims, wherein the
annular guide (58) in the service position bears axially against a shoulder (36) of
a collar (34) of the widened portion (30) of the energy-absorption unit (20) and the
shoulder (36) of the collar (34) of the widened portion (30) of the energy-absorption
unit (20) faces a direction that has an axial component opposite to the stroke direction
(200).
4. The permanent structural link of claim 3, wherein the annular guide (58) is secured
to the collar (34) of the widened portion (30) of the energy-absorption unit (20)
by means of fixing elements (66).
5. The permanent structural link of claim 4, further comprising a mounting plate (62),
wherein the collar (34) of the widened portion (30) of the energy-absorption unit
(20) is sandwiched between the mounting plate (62) and the annular guide (58) and
the fixing elements (66) secure the annular guide (58) to the mounting plate (62)
through holes (38) provided in the collar (34) of the widened portion (30) of the
energy-absorption unit (20).
6. The permanent structural link (18) of any one of claims 3 to 5, wherein the collar
(34) of the widened portion (30) of the energy-absorption unit (20) is welded, preferably
butt welded with an end of the permanently deformable cylinder (20).
7. The permanent structural link (18) of any one of claims 1 to 5, wherein the energy
absorption unit (20) is formed in one piece.
8. The permanent structural link (18) of any one of the preceding claims, wherein the
annular guide (58) in the service position bears axially against a shoulder (56) of
the end portion (44) of the piston (24), wherein the shoulder (56) of the end portion
(44) of the piston (24) faces a direction that has an axial component opposite to
the stroke direction (200).
9. The permanent structural link (18) of any one of claims 3 to 6 in combination with
claim 8, wherein the annular guide (58) bears axially against the shoulder (56) of
the end portion (44) of the piston (24) with a predetermined axial preload and the
piston head (52) in the service position bears axially against a shoulder (54) of
the widened portion of the energy-absorption unit with a predetermined axial preload,
equal in magnitude to the axial preload between the annular guide (58) and the shoulder
(56) of the end portion (44) of the piston (24).
10. The permanent structural link (18) of the preceding claims, wherein the annular guide
(58) is made of a material having a Vickers hardness greater than 600 HV, preferably
greater than 630 HV.
11. The permanent structural link (18) of any one of the preceding claims, wherein the
piston head (52) in the service position is press-fitted into the widened portion
(30) of the energy-absorption unit (20).
12. The permanent structural link (18) of any one of the preceding claims, wherein the
non-deformable piston head (52) is preferably made of a material having a Vickers
hardness greater than 650 HV, preferably greater than 700HV.
13. The permanent structural link (18) of any one of the preceding claims, further comprising
a coupling eye (48) integral with an end (46) of the piston (24) opposed to the end
portion (44).
14. A rail vehicle assembly (10) comprising a first subassembly and a second subassembly
of a rail vehicle assembly, wherein the first subassembly and the second subassembly
consist either of a first vehicle body (12) and a second vehicle body (14) or of a
vehicle body (12) and a running gear (16), characterised in that the rail vehicle assembly (10) further comprises a permanent structural link (18)
according to any one of the preceding claims for linking the first subassembly with
the second subassembly.
15. The rail vehicle assembly of claim 14, wherein the reference axis (100) of the permanent
structural link (18) is parallel to a median vertical longitudinal plane of the rail
vehicle assembly (10), and preferably parallel to a longitudinal axis of the rail
vehicle assembly (10).